Process for obtaining vernonia anthelmintica seed oil



United States Patent 3,230,239 PROCESS FOR OBTAINING VERNONIA ANTHELMINTICA SEED OIL Charles F. Krewson, Abington, and William E. Scott,

Levittown, Pa., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Aug. 19, 1963, Ser. No. 303,187 2 Claims. or. 260-348) (Granted under Title 35, US. Code (1952), sec. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublieenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to refining a vegetable oil. More particularly, this invention relates to purification of Vernonia anthel'mz'ntica seed oil.

The oil of Vernonia anthelmintica seed is of special commercial significance because of its trivernolin con tent, usually two-thirds or more of the weight of the oil. Trivernolin is a naturally occurring 12,13-epoxyoleic triglyceride. Epoxidized oils, as is well known, are used commercially in plastic and surface-coating formulations. Trivernolin, its partial hydrolysis product, divernolin, and vernolic acid have been separated and used for these purposes.

Since the trivernolin is such a predominant part of the oil, the whole oil can be used if the unsaponifiables are removed. The unsaponifiable fraction in most vegetable oils comprises about 1-2% of the weight of the oil. In oil from Vernonia anthelmintica the unsaponifiables represent 68% of the weight of the oil. The unsaponifiables are detrimental to the value of the oil as a stabilizer-plasticizer for poly (vinyl chloride) formations, interfering with compatibility and other desirable prop erties of the oil. Usual refining procedures involve alkaline treatment, sometimes followed by acid treatment, which are undesirable for the present oil because of degradation of the oxirane ring. Refining also includes a bleaching operation employing adsorbents to remove plant pigments. Loss of oil in this operation is usually about one-third of the weight of adsorbent. An improved process for extracting and refining vegetable oil is needed in order to utilize Vernonia anthelmintica seed oil to its greatest potential.

An object of the present invention is to provide a simple procedure for obtaining Vernonia anthelmintica seed oil substantially free of unsaponifiables. Another object is to remove unsaponifiables Without adversely affecting the epoxy functions. Other objects and a fuller understanding of the invention will be apparent from the following description and claims.

We have discovered that cooling a petroleum ether solution of Vernonia anthelmintica oil to about 6() C. results in precipitation of essentially all of the triglycerides while the unsaponifiables remain in solution and are removed by separating the mixture, as by filtration or centrifugationv While the oil is much improved in color, in a single precipitation process some of the plant pigments such as chlorophyll are retained in the oil by occlusion in, or adsorption onto, the precipitate.

We have furthermore discovered, however, that an oil substantially free of chlorophyll can be obtained from the seed by first conducting a solvent extraction of the oil from the seeds at a temperature below about 8 C. Since extraction at this temperature prevents enzymatic hydrolysis of triglycerides, the extract is also very low in free fatty acids. Combining these separate features in an extraction and purification process provides an oil "ice of improved (decreased) color and odor, low content of free fatty acids, and markedly enhanced content of oxirane oxygen.

Since the glycerides of most other fats and oils obtained from plants are more soluble in petroleum ether than the oxirane oxygen containing glycerides of Vernom'a anthelmintica, the cold solvent extraction can be used advantageously to obtain other vegetable oils substantially free of chlorophyll and containing a minimum of plant pigments.

According to the present invention a vegetable oil substantially free of unsaponifiables is obtained by a process comprising comrninuting an oil-containing plant tissue, as soon as possible thereafter combining the comminuted plant tissue with petroleum ether at a temperature below about 8 C., extracting the plant tissue with petroleum ether at about 8 C. or lower temperature to obtain an extract substantially free of chlorophyll, polishing the extract, cooling the extract to a temperature sufficient to the precipitate substantially all the glycerides to obtain a mixture of solids and liquid, separating the solids from the mixture, and allowing the solids to liquefy to obtain a purified oil.

In a particular embodiment of the present invention Vernom'a anthelmintica seed oil substantially free of unsaponifiables is obtained by a process comprising comminuting the seed, as soon as possible thereafter combining the comminuted seed with petroleum ether at a temperature below about 8 C., extracting the seed with petroleum ether at said temperature to obtain an extract substantially free of chlorophyll, polishing the extract, cooling the extract to about 60 C. to obtain a mixture of solids and liquid, separating the solids from the mixture, and allowing the solids to liquefy to obtain a purified oil.

Compared with an oil obtained by the usual process, i.e., by comminuting the seed, extracting with solvent at room temperature or higher, polishing, and stripping off the solvent, the oil of the present process is characterized by a markedly higher oxirane oxygen value (0.3 to 0.5% increase), a lower iodine number, less free fatty acids, and improved color and clarity.

The removal of unsaponifiables according to the present invention is applicable to oils previously separated from Vernonia anthelmintica seed and to inclusion as part of batch or continuous extraction and oil recovery procedures.

This procedure for removing unsaponifiables is con sidered generally applicable in the purification of vegetable oils whether obtained from the seed or from other plant tissue.

The seed is comminuted for solvent extraction by grinding, crushing, flaking or otherwise decreasing dimensions of the seed and exposing large areas of surface to the solvent. Vernom'a anthelmintica seed contains a lipase, apparently bound in the seedcoat, which acts rapidly at room temperature once it is liberated by the comminution process. Investigations conducted previously revealed that the enzyme could be inactivated by high temperatures, such as steam at -120 C. and dry heat at 150 C., so that on comminution and extraction there was obtained an oil containing only 1% free fatty acids as compared to about 2 to 3.5% free fatty acids in oil extracted in one to two hours after comminution of seed in which the lipase had not beeen inactivated. However, rapid extraction of freshly comminuted cold (about 08' C.) seed with cold (08 C.) solvent, preferably initiating extraction within about 10 minutes or less, minimizes lipase action so that oil containing less than 1% free fatty acid has been prepared.

Prevention of hydrolysis is particularly important in the embodiment of the present process in which the extraction is conducted at temperatures below about 8 C. to prevent extraction of chlorophyll from the seed. All of the naturally occurring Vernonia anthelmintica seed oil is indicated to he soluble in the petroleum ether (primarily hexane) fraction commonly used in industry for this purpose. Divernolin, a product of lipase action, is much less soluble, precipitating at 20 C. and below. Rapid extraction minimizes formation of diver nolin. Hence, extraction can be conducted at 8 C. to obtain a high yield of oil containing very little free fatty acid and substantially free of chlorophyl.

The extract typically contains suspended material, the amount of fines depending on variables such as means of comminuting the seed and the type of extracting equipment employed. Hence, a polishing or clarifying step is preferably included in the process. Filter aid may be added prior to or during this step to facilitate clarification and to remove plant pigments.

The polished extract is cooled to about 60 C. and allowed to stand at this temperature. While the precipitations (crystallizations) were carried out by allowing the mixture to stand overnight, this is more a matter of convenience than necessity. Good yields can be obtained at this temperature in a much shorter time.

The solubility of the glycerides in petroleum ether appears to be primarily dependent upon temperature. The ratio of volume of petroleum ether to amount of glycerides may be varied over a wide range with excellent results in solution (extraction) or precipitation of the oil.

Petroleum ether is a preferred solvent for the process of the invention because of its availability and solubility characteristics. The fraction boiling in the range of 35- 59 C. is particularly preferred because it is easier to use in an extractor than high boiling petroleum ethers.

The following examples are presented in illustration of the practice of the invention, but are not intended to be limitations thereof.

Example 1 25 ml. of petroleum naphtha (B.P. 3559 C.) and the solution chilled to about 60 C, and allowed to stand for 2-3 hours at this temperature. The fatty components which precipitated were filtered off at about 60 C., washed with a small portion of cold solvent and stripped of solvent under vacuum of a rotating evaporation at room temperature. The refined oil obtained (6.2 grams, 89.9%) had the following properties:

Oxirane oxygen (percent) 4.26 Free fatty acids (percent) 1.38 Iodine value (Wijs) 88.72

The solvent was removed from the combined filtrate and washings yielding a fraction consisting of unsaponifiable material (0.70 gram, 10.1%) with the following properties:

Oxirane oxygen (percent) 0.07 Free fatty acids (percent) 3.67 Iodine value (Wijs) 198.4

These data indicate almost complete removal of the fatty components from the unsaponifiable material.

Example 2 Vernonia seed oil (1700 grams having an oxirane oxygen percentage of 3.85, a free fatty acid value, calculated as epoxyoleic acid, of 0.86%, and an iodine value, Wijs method, of 104.1) obtained by rapid extraction of freshly flaked seed with petroleum naphtha (B.P. 3569 C.) followed by filtration and removal of solvent, was dissolved in 6 liters of petroleum naphtha; an original seed extract could have ben concentrated to about this same 3.5 ml. of solvent to 1 ml. of oil ratio. The oil solution was chilled with mechanical stirring to about C. and allowed to stand at this temperature overnight. The solids were filtered off at about -60 C., washed with small amounts of cold solvent (-60 C.) and finally stripped of solvent under high vacuum on a rotating evaporator at room temperature; the resulting refined oil weighed 1500 (88.9%) grams and had the following properties: oxirane oxygen (percent), 4.40; free fatty acid (percent), 052; iodine value, 87.80.

The solvent was evaporated off from the filtrate under reduced pressure to give 188 grams (11.1% of the starting oil) of unsaponifiable material fraction having a low oxirane oxygen value of 0.29% and elevated iodine number, 190.0, indicating the presence of only a small amount of epoxy fatty material; i.e., good separation.

Application of the inventive concepts contained in the examples to a continuous process will be obvious to those skilled in the art.

We claim:

1. A process for obtaining Vernonia anthelmintica oil substantially free of chlorophyll and unsaponifiables and having a markedly enhanced oxirane oxygen value, comprising comminuting cold Vernonia anthelmintica seed of a temperature ranging from about 0 C. to 8 C. to prepare it for solvent extraction, extracting the cold comminuted seed within about 10 minutes after its comminution with cold petroleum ether of a temperature ranging from about 0 C. to 8 C. to obtain an extract substantially free of chlorophyll, polishing the extract, cooling the polished extract to at least a temperature sufficient to precipitate substantially all the glycerides to obtain a mixture of solids consisting essentially of the glycerides and a liquid containing substantially all the un saponifiables, separating the solids from the mixture, and liquefying the separated solids to obtain a purified oil.

2. The process of claim 1 wherein the polished extract is cooled to about 60 C.

References Cited by the Examiner UNITED STATES PATENTS 2,152,666 4/1939 Rosenthal 2604l2.4 2,254,245 9/1941 Rosenthal 260-4l2.4 2,479,519 8/1949 Schopmeyer 2604l2.4

CHARLES B. PARKER, Primary Examiner.

ANTON H. SUTTO, Assistant Examiner. 

1. A PROCESS FOR OBTAINING VERNONIA ANTHELMINTICA OIL SUBSTANTIALLY FREE OF CHLOROPHYLL AND UNSAPONIFIABLES AND HAVING A MARKEDLY ENHANCED OXIRANE OXYGEN VALUE, COMPRISING COMMINUTING COLD VERNONIA ANTHELMINTICA SEED OF A TEMPERATURE RANGING FROMABOUT 0*C. TO 8*C. TO PREPARE IT FOR SOLVENT EXTRACTION, EXTRACTING THE COLD COMMINUTED SEED WITHIN ABOUT 10 MINUTES AFTER ITS COMMINUTION WITH COLD PETROLEUM ETHER OF A TEMPERATURE RANGING FROMABOUT 0*C. TO 8*C. TO OBTAIN AN EXTRACT SUBSTANTIALLY FREE OF CHLOROPHYLL, POLISHING THE EXTRACT, COOLING TH POLISHED EXTRACT TO AT ELAST A TEMPERATURE SUFFICIENT TO PRECIPITATE SUBSTANTIALLY ALL THE GLYCERIDES TO OBTAIN A MIXTURE OF SOLIDS CONSISTING ESSENTIALLY OF THE GLYCERIDES AND A LIQUID CONTAINING SUBSTANTIALLY ALL THE UNSAPONIFIABLES,SEPARATING THE SOLIDS FROM THE MIXTURE, AND LIQUEFYING THE SEPARATED SOLIDS TO OBTAIN A PURIFIED OIL. 